NPPB and hydrops fetalis: The results on the efficacy of screening programmes for AF have been conflicting.7–9 N-terminal pro–B-type natriuretic peptide (NT-proBNP) is regarded as the most well-established plasma protein biomarker for predicting AF and HF.10–14 The discovery of new biomarkers could improve risk stratification and screening,15,16 while also improving our understanding of the underlying pathology driving AF and HF.17